My worry with Walmart is that in 4-6 years from now it would make sense to start outsourcing more and more of their loads to subhaulers and finally do away with in house drivers altogether. Walmart has already said they would love to have automated trucks and DC. I think we could be there in the next decade.
Getting rid of their drivers early would eliminate the PR nightmare of laying off workers in favor of machines. They'd only be changing subhaulers for automated trucks. No PR problems there. Also they can shift there equipment cost from conventional to automated.
The one hope I see is if they want to do the automated trucks in house and want a person ready to take over incase the computer has issues.